[Zeke]

With few notable exceptions, going back and forth between stock cars and open wheelers doesn't seem to work. Older days told a different story with Foyt, Gurney and Andretti. But not so much now. Thinking Patrick, Franchetti, Montoya, etc.

A contemporary exception is Tony Stewart but then again, that's a couple of decades past.

Conversely, F1 driver conquer Indy cars. Still Indy car drivers moving to F1 die on the vine. But even an F1 driver who then raced Indy and finally tried stock cars met is undoing.

So, bringing Johnson to Indy (contrived or voluntary, or both) is just not going to work, especially for a 40 year old. Given 3 or so months of constant training, I could probably be within a half second of Johnson with a top engineer. (Well, could of in my track days.)